Lawsuit Filed to Protect Wildlife and San Pedro River from Sprawling Development

Conservation groups cite violations of Endangered Species Act


Chris Eaton, Earthjustice associate attorney, 303-996-9616


Robin Silver, Center for Biological Diversity Co-Founder & Board Member, (602) 799-3275


Sandy Bahr, Sierra Club, Grand Canyon (Arizona) Chapter director, (602) 999-5790


Karen Fogas, Tucson Audubon Society Executive Director, (605) 728-5589

A lawsuit against the U.S. Army Corps of Engineers and the U.S. Fish & Wildlife Service was filed today in federal court in Arizona to protect the San Pedro River, and the wildlife and millions of migratory birds that depend on it.

The suit, filed by six conservation groups, challenges an Army Corps permit, approving destruction of desert washes for development of the Villages at Vigneto, a 12,324-acre residential and commercial community planned in the desert landscape near the town of Benson along the San Pedro River in southeastern Arizona.

The washes, protected by the Clean Water Act, safeguard flows to the San Pedro. The San Pedro River is the last major free-flowing river in the Southwest and provides vital habitat to nearly 45 percent of the 900 species of migratory birds in North America. 

The massive development—which will include 28,000 homes, golf courses, vineyards, resorts, and commercial buildings—will hugely increase Benson’s population from 5,000 to as many as 75,000. Doing so is forecast to increase groundwater pumping from approximately 800 acre-feet to as high as 13,000 acre-feet per year, sucking water from aquifers that maintain the San Pedro’s streamflows. It also would increase stormwater runoff, flooding, and destructive sediment accumulation in the river.

“The Villages at Vigneto will be stealing federally reserved water from the adjacent San Pedro Riparian National Conservation Area, degrading habitat for hundreds of migratory bird species. It will be contributing to more unmitigated sprawl in a watershed with some of the most impressive species diversity in the United States,” said Robin Silver, co-founder and board member of the Center for Biological Diversity.

The lawsuit alleges that the Corps failed to consider the impacts of Vigneto’s development and groundwater pumping on endangered wildlife that rely on the San Pedro to survive.

The Corps’ permit approval has sparked controversy within the federal government. EPA initially opposed the Corps granting the permit to bulldoze desert washes because doing so would damage important aquatic resources. Last year, the U.S. Fish and Wildlife Service wrote the Corps warning of project’s impacts to imperiled wildlife, a warning the Corps ignored.

The San Pedro River watershed is one of the most biodiverse areas in the arid Southwest. This watershed sustains intact stands of cottonwood/willow riparian forest and is home to more than 80 species of mammals and 40 species of reptiles and amphibians.

Recognizing the river’s importance, Congress designated 36 miles of the river as the San Pedro Riparian National Conservation Area in 1988.

Among the San Pedro River species threatened by the development are the western yellow-billed cuckoo, northern Mexican gartersnake, and southwestern willow flycatcher.

“Development and other diversions have dried up and destroyed other important Arizona rivers and the habitat they provided. We cannot and must not allow that to happen to the San Pedro,” said Sandy Bahr, director for Sierra Club’s Grand Canyon Chapter. “The San Pedro River provides important habit for a diversity of plants and animals, a flyway for migratory birds, and recreational opportunities—birding, wildlife viewing, hiking—for people from around the world. The proposed Vigneto development is a real and significant threat to the river, and the plants, animals, and activities the river supports.”

Numerous conservation easements—including mitigation land for the proposed development—are located downstream and would be affected by the depletion of stream flows.  Many of the easements were specifically established to offset impacts to endangered and threatened species from other developments in Arizona.

“The lower San Pedro watershed supports the last intact desert river ecosystem in the Southwest,” said Peter Else, chair of the Lower San Pedro Watershed Alliance, a landowner-based conservation association. “Our members are aware of the rapid loss of water resources and habitat that has taken place in every river valley of Arizona's growth corridor. Preserving this critical resource as required under the Endangered Species Act will protect wildlife habitat and migration corridors, sustainable rural lifestyles and valuable recreation opportunities.”

“What is most alarming about this proposal for those along the Lower San Pedro River is that a new upstream city of 70,000 people will be pulling water from the ground in an unsustainable way. Most of that water will never be replaced. This is not merely a Benson issue. It potentially affects everyone living along the river and what they value,” said Mick Meader, co-president of the Cascabel Conservation Association.

The San Pedro watershed also provides habitat for endangered and threatened species, such as the jaguar, ocelot, and lesser long-nosed bat, which could be adversely affected by construction of a massive development.

“The San Pedro River Valley supports two Globally Important Bird Areas. The valley is a critical migratory corridor for millions of birds, including the threatened western yellow-billed cuckoo. Despite prodding by the U.S. Fish and Wildlife Service and numerous conservation organizations, the Army Corps has failed in its duty to formally consult on the potential impacts the Villages at Vigneto mega-development could have on numerous threatened and endangered species. Apparently litigation is required for the Corps to meet its obligation to fully gauge and minimize the impacts of this development,” said Karen Fogas, executive director of the Tucson Audubon Society.

The developer, El Dorado Benson, LLC, is relying on a Clean Water Act permit issued by the Corps of Engineers in 2006. Since then, the plans have been altered to make the development 50 percent larger, and new information has surfaced on the impacts to endangered and threatened species that inhabit the watershed. Under the Endangered Species Act, these new scientific data trigger mandatory consultation with the Fish and Wildlife Service before any development can proceed.

“Allowing such a massive development to proceed without first considering whether it might harm these sensitive species and their habitats is completely irresponsible and places the entire middle San Pedro ecosystem at risk,” said Chris Eaton, an attorney with Earthjustice representing the groups. “We are simply asking the court to require the Corps and FWS to address these risks before they allow El Dorado to start bulldozing habitat.”

Earthjustice filed this lawsuit on behalf of the Center for Biological Diversity, Sierra Club, Maricopa Audubon Society, Tucson Audubon, Lower San Pedro Watershed Alliance, and Cascabel Conservation Association to force the federal agencies to complete the required consultation before the development may proceed.

Read the legal document.

The San Pedro River
(BLM / CC BY 2.0)
The San Pedro River (BLM / CC BY 2.0)

Additional Resources

About Earthjustice

Earthjustice is the premier nonprofit environmental law organization. We wield the power of law and the strength of partnership to protect people's health, to preserve magnificent places and wildlife, to advance clean energy, and to combat climate change. We are here because the earth needs a good lawyer.